The present invention relates to a washing machine which has means for removing a hardness component from the water which is used for the washing.
It is known that divalent positive ions, such as calcium ions and magnesium ions, have a large affect on the detergency of a detergent, since they act as a hardness component. Since these ions react with a surfactant to generate a water insoluble metallic soap, the contribution of the surfactant is reduced and the detergency is lowered. In a synthetic detergent, in order to reduce the hardness, a zeolite as one of the builders is blended. The zeolite is a minute white color particle in which silicic acid and aluminum form main components, and a sodium ion in the zeolite and polyvalent positive ions, such as the calcium ions and the magnesium ions, in the water perform an ion-exchange, so that the water is softened. However, while the zeolite removes the polyvalent positive ions, since these polyvalent positive ions react with the surfactant of the detergent, the generation of the metallic soap can not prevented completely. It is preferable to perform the washing by dissolving the detergent in water from which the ions have already been removed. Further, since the zeolite mingles with the detergent, there is a problem in that the zeolite particles adhere to the clothes after the washing.
A washing machine in which these metal ions are removed before the washing is carried out is described in Japanese application patent laid-open publication No. Hei 11-151397. In this washing machine, a hardness judgement means is provided for judging the hardness of the water, and a water softening means is used to produce soft water from the hard water. Further, in this washing machine, in addition to the water softening means, a regeneration mechanism is provided for regenerating the positive ion exchange resin which is used in the water softening means. This regeneration means is constituted by a salt supply means for supplying the salt which is used for the regeneration of the positive ion exchange resin and a water discharge passage for discharging the water from the positive ion exchange resin to the outside of the washing machine during the regeneration. Further, in detail, a salt case is provided in which a salt solution liquid or a common salt is accommodated in advance, and from this salt case, a one time part salt solution liquid or a one time part common salt is discharged, and the salt solution liquid or the common salt is supplied to a water softening portion along with the water which passes through the feed water passage, whereby the positive ion exchange resin is regenerated.
In the washing machine according to the above-stated technique, when the hardness of city water exceeds the water softening ability of the positive ion exchange resin, by reducing the amount of water used for the washing, the effectiveness of the detergent is increased, up and the washing is carried out over a longer period of time; however, full consideration has not been given to the formation of the soft water when the water hardness is very high.
Further, although consideration is given to the softness of the water for preventing a drop in the cleaning effect of the detergent, no consideration has been given to the formation of soft water for use in rinsing and the effects thereof. In this regard, the hardness component has a unfavorable affect on rinsing. The rinsing is carried out to exclude the dirty components, which are removed from the clothes by the washing, so that they will not adhere again to the clothes, and further to remove the detergent which is adsorbed on the clothes. The surfactant in the detergent which is adsorbed on the clothes is diluted by the rinsing water and is separated from the clothes. At this time, in rinsing water which contains a large water hardness component, the hardness component and the surfactant are combined, so that a metallic soap is formed. When the surfactant is adsorbed on the clothes and the metallic soap is formed, it is difficult to remove the metallic soap.
Accordingly, after the rinsing, the metallic soap still adheres to the clothes, and the feeling of the clothing becomes bad (a stiff feeling), and the wearing of the clothes feeling.
For example, generally in Europe and the United States of America a, the water has very high hardness compared to the water in Japan.
More particularly, in a drum type washing machine which is the main type of machine used in Europe, by using hot water, a reduction in the cleaning ability is prevented. However, to raise the temperature of the water, it is necessary to use much electric power. For example, to raise 30 liters of water from 20xc2x0 C. to 60xc2x0 C., when the adiabatic is performed perfectly, it is necessary to use about 1.4 kWh of electric power. This means that with respect to the consumption of electric power for the washing alone using the water, heating the water requires about ten times the amount of electric power. Recently, to prevent global warming, it is required to perform energy saving in the operation of electrical products. For these reasons, in a drum type washing machine, it is desirable to lower the temperature of the washing water. For this purpose, it is necessary to heighten the detergency in a way other than by the use of hot water.
A first object of the present invention is to provide a washing machine wherein, although water having a high hardness may be used, a high cleaning effect can be obtained.
Further, a second object of the present invention is to provide a washing machine wherein, in addition to a heightening of the cleaning effect using a detergent, the washing performance, including rinsing, can be improved.
To attain the above-stated first object, in a washing machine having a washing tub for receiving objects to be washed and for carrying out a washing of these objects, a feed water device is provided for supplying water to the washing tub, and a drainage means is used for discharging water from an inner portion of the washing tub. The washing machine is characterized in that the feed water means comprises a feed water valve, a vessel for injecting a detergent on a downstream side of the feed water valve, and an ion removal means for removing ions which are contained in the feed water, the ion removal means being provided between the feed water valve and the detergent injecting vessel.
Using a control means for controlling the washing process, in the supply of water during the washing process, the water supply is interrupted once, the washing process is carried out to a midway point in the cycle, after which the water supply is started again and water is supplied in a regular amount.
Further, to attain the above-stated second object, after completion of the washing process, the ion removal means is regenerated, and, in a rinsing process, soft water in which the ions are removed is supplied.
As the above-stated ion removal means, an ion exchange material is used, while in a regenerating process, a regeneration processing agent is used, and the ion exchange function of the ion exchange material is regenerated. Further, as the regeneration processing agent, for example, salt or salt water can be used. However, to make the ion removal means compact, it is preferable to store the salt or the water each time the regeneration is performed, and to produce the salt water in the case of the use salt water.